1. Field of the Invention
The present invention relates to a wireless communication apparatus and a method thereof, and, more particularly, to a wireless communication apparatus, a method thereof and a wireless communication system employing the same wherein a data processing unit can judge correctly whether data has been sent in a Bluetooth system. The present application is based on Korean Patent Application No. 2001-6519 filed Feb. 9, 2001, which is incorporated herein by reference.
2. Description of the Related Art
Bluetooth communication has recently been popular as a local wireless communication, and can wirelessly transmit information such as audio data and video data within the range of 10 m to 100 m with the speed of up to 1 Mbps.
The existing Bluetooth system uses ISM (Industrial Scientific Medical) band of 2.4 GHz.
FIG. 1 is a view showing the structure of a Piconet of a Bluetooth communication system.
Referring to FIG. 1, in a Bluetooth communication system, a Piconet is formed such that a multiple of slave devices (S1–S7) are connected to a master device (M). At most, seven slave devices (S1–S7) can be connected to the master device (M) in an active mode in one piconet.
In the Piconet, the master device (M) and the slave devices (S1–S7) communicate through a packet.
FIG. 2A is a view showing the structure of a conventional packet transmitted in the Piconet of FIG. 1.
FIG. 2B is a view showing a header part of the packet in detail.
Referring to FIG. 2B, a packet header has a total of 18 bits of AM_ADDR, TYPE, FLOW, ARQN, SEQN, and HEC.
ARQN having a payload is an acknowledge indicator of 1 bit, and is used for notifying a source of a successful transmission without CRC (Cyclic Redundancy Check) error.
A response message having acknowledge information takes two forms of acknowledgement: positive acknowledgement (ACK) and negative acknowledgement (NAK). The ACK is set as ARQN=1, and the NAK is set as ARQN=0.
Moreover, in a current Bluetooth communication, the master device and the slave devices perform bi-directional communication by a TDD (Time Division Duplex) method as shown in FIG. 3.
The master device designates and transmits data to a target slave device in the Tx slot. In FIG. 3, 1 and 2 in the target Tx slots of the master are designated for slave 1 and slave 2, respectively.
The slave devices designated by the master device receive the corresponding data in an Rx slot.
FIG. 4 is a view showing a protocol stack of a Bluetooth communication system.
LMP (Link Manager Protocol) establishes a link between a source wireless communication apparatus and a destination wireless communication apparatus, and manages security and control thereof.
The LMP defines a packet containing a response message to a request-to-send message.
After sending the request message, the source wireless communication apparatus receives the response message from the destination wireless communication apparatus within a predetermined time, in other words within a LMP response time. Therefore, the source wireless communication apparatus confirms the acknowledge information of the request message, or whether the request message is received by the destination wireless communication apparatus, then determines whether to re-send the request message or to perform the next operation according to the message flow.
On the other hand, in the LMP (Link Manager Protocol), when a piconet does not have a response message, the source wireless communication apparatus confirms whether the destination wireless communication apparatus received a signal, a base band (refer to FIG. 4) judges acknowledge information included in the header of a Null packet, or an ARQN value included in the header is judged and acknowledge information is offered to the LMP (Link Manager Protocol).
In addition, when sending request information, that is, when sending more than two different data messages consecutively, after receiving request message data from another wireless communication apparatus, a wireless communication apparatus having a Bluetooth module processes the received null packet in the base band after sending the first message and offers acknowledge information to the LMP (Link Message Protocol).
Then, the LMP (Link Message Protocol) determines whether to send a second message using acknowledge information received from the base band or to send the first message again.
As described above, if a request message not having a response message is sent in a conventional Bluetooth communication mode, it can be checked whether the request message has been sent successfully by the transmission of the acknowledge information from the base band to the LMP (Link Message Protocol).
Therefore, it causes overload in the base band, and there is increased signaling interface between the base band and the LMP (Link Message Protocol).